During normal operation of a motor vehicle, it is common that all four wheels may not be turning at an identical rate of speed. Different wheel turn rates are most commonly encountered when the vehicle is making a turn, but may also be caused by braking or non-uniform road surface conditions. In order to accommodate differing wheel spin rates while continuing to direct power to two wheels it is possible to provide a differential that allows for different wheel turn rates between the powered wheels. The differential allows the wheels to spin at independent rates while delivering power to each wheel. While this solution may be satisfactory in some driving conditions, it is unsatisfactory under conditions where one of the powered wheels experiences a surface having a much lower coefficient of friction than a surface being experienced by the other wheel(s). Such conditions may prevent the application of torque to the wheel with the most traction, thereby resulting in unacceptable vehicle performance.
The differential may be locked to prevent different spin rates such that the wheels are forced to rotate in unison, thus ensuring that the wheels effectively apply torque to the ground surface and vehicle control is maintained. A wide variety of electrical and mechanical systems may be used to lock a differential. Unfortunately, merely activating an actuation system does not always guarantee that the differential is actually locked. For various reasons, including the fact that gear faces may be misaligned, a vehicle controller may send an activation signal to lock the differential, without resulting in the differential being successfully locked. Therefore, the vehicle may incorporate complex systems to monitor the actual status of the differential. For example, it is possible to verify the lock status of a differential by employing an independent switch. However, such a switch requires additional wiring to the control system, which is commonly positioned remotely. Other systems utilize other independent signals such as wheel speed sensors to monitor the actual status of the differential, but these systems incur additional complexity and cost to receive and analyze data generated by the wheel speed sensors.
In general, present differential monitoring and sensing systems add undesirable complexity to vehicle design and additional components that may suffer from wear and damage.